Actually, although air-cooled airplane engines indeed have clearances a
little looser than liquid-cooled engines, the reason for the really thick
feelers is to pre-set hydrauklic lifters.; They're not pumped up when
you're building the engine, and when hydraulic lifters are squashed down the
clearance is indeed that big.
Those tools are mostly for modern Continentals and Lycomings, which mostly
all have hydraulic lifters. Generally, the really old engines have solid
lifters, though. My old Army-surplus plane's 220-HP Continental radial
engine has solid lifters and the valve clearance is .010 cold. The pushrods
and cylinders are both steel, so there's not much differential expansion
changing the clearance between cold and hot. Now, when you have aluminum
pushrods in a steel or iron engine, it's a different story, but that's not
common on certificated aircraft engines.
That big radial is indeed a bit noisy on start-up as Rex noted, and the big
whoof of oil smoke is certainly remarkable (they do that), but it never
quiets down much till I land and shut it down. ;-)
Karl
> On 11/19/2008 Elton E. (Tony) Clark wrote:
>> *****Back to the original message:*
>> *Did anyone else have a problem with tappet settings of .060", .080"
>> and
>> .200"????????????
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